Coatings for glass-shaping molds and molds comprising the same

Abstract

Described are glass-forming molds made of a graphite mold body and a coating formed by atomic layer deposition, with the coating being made of alumina or a combination of alumina and yttria.

What is claimed is: 
     
       1. A glass-forming mold comprising:
 a fine-grained graphite mold body having one or more mold features, wherein the fine-grained graphite has a grain size that is not greater than 10 microns; and 
 a coating on the one or more mold features, the coating consisting essentially of alternating layers of alumina and yttria. 
 
     
     
       2. The glass-forming mold of  claim 1 , wherein the coating has a coefficient of thermal expansion that is within 1 part per million/° C. of the coefficient of thermal expansion of the fine-grained graphite mold body. 
     
     
       3. The glass-forming mold of  claim 1 , wherein a thickness of the coating is between 10 nanometers and 500,000 nanometers. 
     
     
       4. The glass-forming mold of  claim 1 , wherein the glass-forming mold is free of surface discontinuities that are greater than about 25 microns from the average surface plane of the glass-forming mold. 
     
     
       5. A method of making a glass-forming mold comprising:
 providing a fine-grained graphite mold body, wherein the fine-grained graphite has a grain size that is not greater than 10 microns; and 
 depositing a coating on the fine-grained graphite mold body by atomic layer deposition, the coating consisting essentially of alternating layers of alumina and yttria. 
 
     
     
       6. The method of  claim 5 , wherein the coating has a coefficient of thermal expansion that is within 1 part per million/° C. of the coefficient of thermal expansion of the fine-grained graphite mold body. 
     
     
       7. The method of  claim 5 , wherein a thickness of the coating is between 10 nanometers and 500,000 nanometers. 
     
     
       8. The method of  claim 5 , wherein the glass-forming mold is free of surface discontinuities that are greater than about 25 microns from the average surface plane of the glass-forming mold. 
     
     
       9. A method of forming a glass article comprising:
 providing a fine-grained graphite mold body, wherein the fine-grained graphite has a grain size that is not greater than 10 microns; 
 depositing a coating on the fine-grained graphite mold body by atomic layer deposition, the coating consisting essentially of alternating layers of alumina and yttria; and 
 contacting a surface of the fine-grained graphite mold body with softened glass. 
 
     
     
       10. The method of  claim 9 , wherein the softened glass is softened alumino-silicate glass.